Advances in technology have enabled the size of personal computers to decrease. As a result, the use of portable computers, such as notebook computers, laptop computers, and notepad computers, is rapidly increasing. The portability of notebook computers and notepad computers enables a user to keep his or her computer readily accessible such that computing resources are effectively always at hand. For example, a notebook computer running on a battery pack enables a user to access computational resources without the need for external sources of electricity.
Many portable computers are configured such that a display screen of the computer pivots, or rotates, with respect to the base of the computer. FIG. 1 is a diagrammatic representation of a portable computer or, more specifically, a notebook computer. A notebook computer generally includes a display assembly and a base assembly. The display assembly typically includes a display screen surrounded by a plastic housing, while the base assembly often includes an input/output device such as a keyboard, and houses a central processing unit and memory devices (not shown). The plastic housing of the display assembly is hinged to a base housing that includes conventional computer components such a keyboard, disk drives, and connector ports. The hinge assembly allows the display assembly to rotate or pivot relative to a base housing and remain in a desired static position. The display housing is movable about the hinge(s) between a closed position against the base housing and an open position with the display and keyboard exposed for use. Hinge assemblies typically have a portion that is secured to the display housing and another portion that is secured to the base housing. Portable computer hinges typically incorporate spring/friction mechanisms for rotating the display housing and for maintaining it in a static position. For large or bulky portable computers, the frictional force in the hinge mechanism that supports the weight of the display housing may be significant that two hands are required to open the computer—one hand to hold the base while the other hand pivots the display about the hinge. This becomes more evident as display assemblies become larger, thereby increasing the weight of the display assembly relative to the base housing. Furthermore, the weight of the display housing has a tendency to slam closed against the computer base, as the friction hinge weakens over time. Also, because the base and display housings are made of light-weight plastics, they cannot withstand the forces required to rotate the display housing. This results in the plastic cracking around the hinge assembly.
When a display assembly is closed over a base housing, a latch mechanism locks the two portions together. Some display assemblies include a display “pop-up” feature as part of a portable computer's overall hinge assembly. When the latch on the display housing is released, a certain amount of force stored in the hinge assembly causes the display assembly to rotate open slightly to provide enough room for a user to grasp the display housing and rotate it open relative to the base housing. The pop-up feature subjects the hinge assembly to relatively large biasing spring forces where plastic display housings are sufficiently compliant to absorb such forces. However, portable computers have display and base housings that are entirely or partially metal-based, with materials such as titanium or aluminum. Metal display housings may not be able to withstand such large biasing forces from a pop-up feature, causing the metal to bend and form permanent arcs.